Sub-pixel point positioning

code example:

#include"opencv2/highgui/highgui.hpp"#include"opencv2/imgproc/imgproc.hpp"#include<iostream>#include<stdio.h>#include<stdlib.h>using namespaceCV;using namespacestd;#defineWindow_name "Shi-tomasi Corner point Detection"Mat src, gray;intMaxcornernum =Ten;intMaxtrackbarnum = -;//scroll bar callback functionvoidCornersrefinement (int,void*) {Mat copy=Src.clone (); if(Maxcornernum <=1) {Maxcornernum=1; }    //Corner Point detection parameter PreparationVector<point2f>Corners; DoubleQualitylevel=0.01;//minimum acceptable feature value for corner detection    DoubleMindistance =Ten;//the minimum distance between corner points    intBlockSize =3;//The specified field range when calculating the derivative autocorrelation matrix    DoubleK =0.04;//weight Factor//perform Shi-tomasi corner detection.Goodfeaturestotrack (gray, corners, Maxcornernum, Qualitylevel, Mindistance, Mat (), BlockSize,false, K); //pixel-level corners are plotted with blue circles.     for(inti =0; I < corners.size (); i++) {Circle (copy, Corners[i],4, Scalar (255,0,0),2,8,0); }    ///precise parameter of corner position.Size winsize = Size (5,5); Size Zerozone= Size (-1, -1); Termcriteria Criteria=Termcriteria (Cv_termcrit_eps+Cv_termcrit_iter, +,//maxcount=40        0.001);//epsilon=0.001    ///calculate the position of the corner point after the precisionCornersubpix (gray, corners, winsize, zerozone, criteria); //sub-pixel corner makes the supply red circle draw     for(inti =0; I < corners.size (); i++) {Circle (copy, Corners[i],4, Scalar (255,0,255),2,8,0); //output angular Point coordinatescout <<" ["<< I <<"]  ("<< corners[i].x <<","<< corners[i].y <<")"<<Endl; } cout<<Endl; Imshow (window_name, copy);}intMain () {src= Imread ("church.jpg",1);    Cvtcolor (src, Gray, Color_bgr2gray);    Namedwindow (Window_name, window_autosize); Createtrackbar ("Maximum Corner points", Window_name, &Maxcornernum, Maxtrackbarnum, cornersrefinement);    Imshow (Window_name, SRC); Cornersrefinement (0,0); Waitkey (0); return 0;}

Effect:

Sub-pixel point positioning